Liquid fuel propellant



1964 w. K. FORTMAN ETAL 3,117,551

LIQUID FUEL 'PROPELLANT Filed Aug. 12, 1960 2 Sheets-Sheet 1 INVENTORSW|LLlAM K. FORTMAN NATHAN\E.L HUGHES 6 w. K. FORTMAN ETAL LIQUID FUELPROPELLANT 2 Sheets-Sheet 2 Filed Aug. 12, 1960 FLAME FRONT FIG. 3

WILLIAM K. FORTMAN NATHANIEL HUGHES INVENTORS.

ATTORNEYS United States Patent Ofiice 3,117,551 LE'QUZB PRQPELL TWilliam K. Fortnian, l vletuchen, NJQZ, and Nathaniel Hughes, New York,N.Y., assignors to General Precision inc, Little Falls, Ni, acorporation of Delaware Filed Aug. 12, E60, Ser. No. 49,346 5 Claims.(Cl. 116-437) The present invention relates to the generation andutilization of audible and ultrasonic waves, and more particularly to anacoustic generator for the generation of audible and ultrasonic wavesand shock waves as well as using these phenomena in a controlled mannerin conjunction with one or more fluid mediums in a treating or reactionzone, e.g., a combustion zone.

It is well known that ultrasonic waves in the audible or ultrasonicrange have many applications, mainly in gaseous state or in mediacontaining suspensions of fluid or solid aerosols. Other applicationsexist in flame vibration in combustion studies where the aim isincreased thermal efficiency. Work has also been done in the field ofsignalling, metallurgy, foam breaking and various chemical effects.

Some of the first ultrasonic generators based on the air jet principlewere suggested by I. Hartmann (2O Phys. Rev. 719-727, 1922 Thesegenerators consist of a jet opposed coaxially by a resonator. When anair jet exceeding the speed of sound is forced through the nozzle and acavity resonator is placed within one of the socalled intervals ofinstability, a harmonic vibration corresponding approximately with thenatural vibrations of the resonator are produced.

In about 1947, Hartmann developed a stem generator which basicallyconsists of a nozzle and a resonator which are coupled coaxially by acentral stem. Studies of this type of generator showed that an air jetvelocity below the speed of sound could produce sound waves. In this wayit differs considerably from the earlier generators which find theirexplanation in the structure of a supersonic jet.

The Yellot and Savory US. Patent No. 2,519,619 made some novelimprovements on the I-Iartmann generator by adding a stem protrudingfrom the resonator towards the nozzle. This patent also teaches the useof regenerator pads and regenerator cylinders which, according to thepatent, provides improved sound generation and the sensitivity of thegenerator to adjustment is lessened. In this type of generator, thenozzle and the resonator are clamped or screwed into a frame permittingadjustment of the gap between nozzle and resonators.

In another version of the Hartmann whistle generators, Dr. R. M. G.Boucher has constructed an independent secondmy resonance chamber intowhich the nozzle and resonator are fitted coaxially opposed. The entirebase is then surmounted by an exponential horn for directional soundemission. The ratio of resonator to nozzle is from 1.33 to 2.5 andhigher efliciencies than any previously reported are claimed for thisdevice.

In most applications where sound is air coupled to the material to betreated, it is desirable to bring the material close to the sound energysource as it is desirable to treat a maximum amount of material in theshortest amount of time. Generally all processes are dynamic and involvemovement of one sort or another. Even in batch processes, the materialundergoing a chemical or other reaction is stirred or aerated. Whetherthe material is gas, liquid or free flowing powder or a mixture of someor all of these, almost without exception it is desirable to keepexposing new interfaces. This is specially true in the treatment ofsolids and liquids and gases with sharp temperature gradients such asflames because a consid 3,1115% Patented-Jan. 14, 1964' erable impedancemismatch is encountered by the sound wave at each interface andboundary.

This is normally achieved by stirring, tumbling, aerating or by someother external energy source which moves the material towards and pastthe sound source. However, even under ideal conditions the moving massis usually influenced by the excess driving gas being discharged atrandom from the sound generator.

In the prior art devices hereinbefore described, little attempt has beenmade to co-relate the fluid supply means and the sound generator, e.g.,whistle. Much energy is lost by allowing the fluid to dissipate atrandom after its release from the resonator cavity. It has now beendiscovered that one or a plurality of fluid mediums can be supplieddirectly towards, to, and past the sound source. Heretofore, inducingsonic vibrations in flames has always presented problems due to theflame layer temperature gradients which present sound impedance barriersto an external sound source. Contrary to the prior art devices, thepresent invention contemplates generating the sound in an activereaction zone, e.g., within the flame envelope. Where flames are inlaminar layers above a disintegrating solid charge, there iscontemplated the sending of a shock Wave between the burning zone andthe flame to cause a quicker gas release, turbulance and physicaldisturbance to increase the reaction rate, e.g., the burning rate. Atthe same time, additional fluids, liquid and gas are introduced into thesound source zone. Th molecular interaction of the reacting particles inthe reaction zone is then increased by passing the particles from thesound source zone past an acoustic treating zone, the geometricconfiguration of the combined sound source zone and acoustic treatingzone being such as to not only impel the fluid particles into thereaction zone, but the sound vibrations impart very high velocities tothe molecules of the reacting components in the reaction zone toincrease the activity therein.

The invention in its broader aspects contemplates feeding into a soundsource zone one or more fluids required for a desired reaction, e.g.,combustion; generating in said sound source zone a sound of highintensity, so directed and controlled as to carry said fluids into anacoustic treating zone of a geometric configuration designed to loosenthe bonds between individual fluid particles and direct said particlesinto a reaction zone, e.g., combustion chamber; at the same time, saidacoustic treating zone beams the sound waves from the sound source zoneinto the reaction zone causing a sound therein of an intensitysuflicient to cause intense molecular activity therein.

Thus, it is an object of the present invention to provide means fortreating one or a plurality of fluids by sound means.

Another object of the present invention is to provide means toaccomplish an efficient bi-propellant injection into an enginecombustion chamber.

The invention also contemplates providing propellant injection meanswhich are particularly useful for rocket engines.

With the foregoing and other objects in view, the invention resides inthe novel arrangement and combination of parts and in the details ofconstruction hereinafter described and claimed, it being understood thatchanges in the precise embodiment of the invention herein disclosed maybe made within the scope of what is claimed without departing from thespirit of the invention.

Other objects and advantages will become apparent from the followingdescription taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a perspective view of a sound source zone and a portion or"an acoustic treating zone contemplated herein showing a portion of anozzle and a section cut through the surrounding casing to illustratethe disposition of the nozzle in the casing;

FIGURE 2 shows a longitudinal sectional view of one embodiment of FIG.1; and,

FIGURE 3 depicts diagramatically what takes place in another type ofacoustic treating zone, the device illustrated being a modification ofthe generic device herein contemplated.

Generally speaking, the present invention contemplates the combinationof a fluid feed nozzle having a plurality of narrow neck feedingorifices discharging into a sound source zone, i.e., where said nozzlespouts, in which there is a stem passing through the jet nozzle, saidstem being preferably hollow and adapted to bring additional fluid tothe sound source zone or pass through said zone into a reaction zone,e.g., combustion chamber. Associated with the sound source zone is anacoustic treating zone including a sound wave radiator having a shockridge surrounding the sound source, a resonator facing the radiator, andadvantageously, a secondary resonance chamber interposed between thefeeding orifices and the stem axially opposed to the resonator. Thegeometric configuration of the sound source zone and the acoutictreating zone is such as to conduct the fluid from the sound source zoneinto the acoustic treating zone while treating the fluid particles at asound intensity suflicient to convert or maintain the fluid in the gasor aerosol phase. In the acoustic treating zone the action of the soundshock 'waves therein created acting on the fluid impart great velocityto the individual molecules of the fluid which is then passed into thereaction zone.

In carrying out the foregoing concept into practice the apparatus ofFIGS. 1 and 2 herein contemplated has a feeding zone 12 contained in ajet nozzle 13. The feed ing zone which is for feeding one or more fluidsto the sound source zone is subdivided into a plurality of longitudinalouter ducts or feeding compartments 1 and 15 which are disposed betweenbody jacket 16 and casing 17 of the nozzle. Although in the drawing onlytwo such duct compartments 14 and 15 are depicted, many more such ductscan be provided by radial dividing walls. Furthermore, the crosssectional area of these ducts need not necessarily be the same. Indeed,they can be so sized as to furnish diflerent fluids into the soundsource zone in various proportions. Passing through the longitudinalcenter of the nozzle is a stem 19' which is preferably hollow andthrough which a second phase fluid can be introduced at any desiredcentral position in a sound source zone Zii, an acoustic treating zone21 or a reaction zone 22. The second phase fluid may be of acharacteristic completely different than the fluids passing through theouter feeding compartments 1% and 15 or causing the sound. In fact, thefluid passing through the hollow stem may even be an inert or noble gas.If the reaction zone already contains or has fed to it from outsidesources a highway reactive material, e.g., a solid propellant, thepresence of an inert gas at the sound source and in the adjacentacoustic treating zone may tend to retard any reaction in these twozones by the fluids fed thereto until these are carried into thereaction zone where the reaction is desired. It is also possible tocirculate a cooling fluid through the stem. The sound forming gas issupplied by means of a compartment 23 surrounding the stem, to the soundsource zone 20. This gas may also be of the kind required for a desiredreaction, e.g., a fuel or oxidizer. Axially opposed to the spoutingwhistle mouth Zita which provides the sound is a resonator 24 which is ahollow cup having a U-shaped cross section. Surrounding the spoutingmouth a is a cylindrical Wall 25b which together with outer Wall 2912 ofspouting mouth Zfla defines a second resonance chamber 25, and machinedin the face of casing 17 is a concave radiator 26, outer feeding ducts14 and 15 discharging their fluid under pressure in the sound zonethrough narrow necks 2'7 located between the second resonance chamber 25and radiator 26. The

4 size of the gap at the narrow neck 27 will be to a large extentdetermined a rocket engine thrust.

To impart swirl to the discharge fluid, vanes 28 are disposed at or pastthe narrow neck 27, depending from the radiator. These vanes helpseparate fluid particles and impart greater activity.

These vanes 28 are shown in FIGURE 1 but purposely omitted from FIGURE 2and FIGURE 3 to show other constructional features of the device.

One feature of the invention which appears to further break up the fluidand increase the molecular activity are a plurality of shock ridges 29on the face of the concave radiator. As illustrated in the drawing, theface of the radiator is not a smooth curve but has a plurality of welldefined circular indentations, i.e., shock ridges around the entire faceof the radiator. These shock ridges 29 appear to play an important partin the activity taking place in the acoustic treating zone. The deviceshown in FIG- URE 2 is readily coupled to a source of air used forproducing the sound by means of threads 39 on the input side of casing17. Fluid is introduced to the feeding compartments 14 and 15 throughthe threaded input sections 31 and 31a. Lines for carrying these fluidsare coupled to these threaded sections.

As illustrated in FIGURE 3, the device contemplated herein isparticularly useful for supplying of a fuel oxidizer mixture to acombustion zone. In FIGURE 3 the fuel and oxidizer are both introducedfrom the outer ducts or feeding compartments. The particular method ofintroducing the oxidizer and fuel depends to a large extent on thecharacteristics of these combustion intermediates.

In the design of a whistle assembly useful as the propellant injectionmeans for rocket engines, use is made of standard tables and formulassuch as are found in Mechanical Engineers Handbook 5th ed. pp. 337-338.These tables and formulas are only a guide however and resort must behad to trial and error. The device contemplated herein when properlysized can be used for a thrust of between lbs. to 150 lbs. for hydrazinefuel and a chlorine trifluoride oxidizer. In this case there is anoxidizer to fuel ratio of three to one. The whistle shown in FIGURE 3 ofthe drawing can deliver 158 db sound at a distance of ten inches fromthe sound source at 42 pounds pressure at a frequency of 12,000 cyclesper second.

The eflect of usin a whistle assembly of the type described herein as aninjection head instead of the conventional injection heads as depictedby Barcel Barrere et al. in Rocket Propulsion, Elsevier Publishing Co.1960 (D. Van Nostrand Co. distributors) pages 383 to 390, is the factthat the sound source keeps the flame front back as shown in FIGURE 3.In the conventional showerhead type of injector, the size of the aerosolis limited by the size of the showerhead apertures. In the injectordescribed herein, the aerosol size is limited solely by the dynamicfactors in the acoustic treating zone. A whistle having a length of4.120 inches and a diameter of 1. 25 inches has a pressure drop of 10.75p.s.i.g., and a flow rate of about 0.5 lb./sec. for a throat of .020inch to deliver a thrust of about lbs. using chlorine trifluoride andhydrazine as the propellant combination. The thrust may be increased byadjusting the throat dimen sions.

It is to be observed therefore that the present inven tion provides foran apparatus 11 for subjecting a fluid medium to the treatment of soundwaves. This apparatus comprises in combination; a feeding zone 12including a nozzle 13, a jacket 16 defining said nozzle body, a casing17 surrounding said jacket, the space between the said jacket and easingdefining an outer duct 14, and a stem 19 passing through the center ofsaid nozzle; a sound source zone 20 where the nozzle spouts and wherethe sound producing gas in said nozzle is forced through from acompartment 23 around said stem to give out a sound of high intensity;and, an acoustic treating zone 21 including a first resonator 24coaxially opposed to said sound source zone 20, a concave radiator 26having shock ridges 2-9 thereon surrounding said sound source and saidouter duct 14, and a second resonance chamber 25 interposed between saidradiator and said outer duct. There may be a plurality of outer ducts 15divided by walls 18 and the cross sectional area of said ducts need notbe uniform. Stem 19 is preferably hollow.

Furthermore, it is to be observed that as used herein, the terms soundand whistle include ultrasonic sounds or devices which produce noaudible sound.

The present joint invention as set forth in this patent application is acontinuation-in-part of the sole Fortmann US. patent application SerialNo. 14,304, filed on March 11, 1960.

Although the present invention has been described in conjunction withpreferred embodiments, it is to be understood that modifications andvariations may be resorted to Without departing from the spirit andscope of the invention as those skilled in the art will readilyunderstand. Such modifications and variations are considered to beWithin the perview and scope of the invention and appended claims.

We claim:

1. In an apparatus for subjecting a fluid medium to treatment by soundwaves, in combination;

a cylindrical jacket defining a nozzle;

2. spouting mouth at one end of said nozzle so formed that a gas fiuidcan be forced through said nozzle and out of said mouth into a zone inthe vicinity of said mouth;

a cylindrical casing surrounding said jacket, the space between saidcasing and jacket defining at least one outer duct with an opening atsaid one end so that a second fluid can be delivered into said zonethrough said opening;

a stem mounted in said nozzle so as to pass axially through said nozzleand mouth; and,

a cylindrical hollow resonator having one closed end and one open end,said stem passing axially through said resonator open end to said closedend, said resonator being mounted on said stem at said closed end, saidopen end being axially opposed to said mouth, so that when a gas isforced out of said mouth into said zone a sound of high intensity isthere created.

2. A device as claimed in claim 1, including a concave radiator in saidcasing surrounding said mouth having a plurality of circular shockridges thereon.

3. A device as claimed in claim 2, including a plurality of vanes insaid outer duct disposed at said opening over said mouth between saidjacket and casing.

4. A device as claimed in claim 3, including a secondary resonancechamber in said jacket surrounding said spouting mouth formed by acylindrical Wall surrounding said spouting mouth and an outer wall ofsaid mouth.

5. A device as claimed in claim 4, said stem being hollow so as todeliver a third fluid past said spouting mouth.

References Cited in the file of this patent UNiTED STATES PATENTS1,796,887 Critchfield Mar. 17, 1931 1,980,171 Amy Nov. 13, 19342,238,668 Wellenstein Apr. 15, 1941 2,532,554 Joeck Dec. 5, 1950

1. IN AN APPARATUS FOR SUBJECTING A FLUID MEDIUM TO TREATMENT BY SOUNDWAVES, IN COMBINATION; A CYLINDRICAL JACKET DEFINING A NOZZLE; ASPOUTING MOUTH AT ONE END OF SAID NOZZLE SO FORMED THAT A GAS FLUID CANBE FORCED THROUGH SAID NOZZLE AND OUT OF SAID MOUTH INTO A ZONE IN THEVICINITY OF SAID MOUTH; A CYLINDRICAL CASING SURROUNDING SAID JACKET,THE SPACE BETWEEN SAID CASING AND JACKET DEFINING AT LEAST ONE OUTERDUCT WITH AN OPENING AT SAID ONE END SO THAT A SECOND FLUID CAN BEDELIVERED INTO SAID ZONE THROUGH SAID OPENING; A STEM MOUNTED IN SAIDNOZZLE SO AS TO PASS AXIALLY THROUGH SAID NOZZLE AND MOUTH; AND, ACYLINDRICAL HOLLOW RESONATOR HAVING ONE CLOSED END AND ONE OPEN END,SAID STEM PASSING AXIALLY THROUGH SAID RESONATOR OPEN END TO SAID CLOSEDEND, SAID RESONATOR BEING MOUNTED ON SAID STEM AT SAID CLOSED END, SAIDOPEN END BEING AXIALLY OPPOSED TO SAID MOUTH, SO THAT WHEN A GAS ISFORCED OUT OF SAID MOUTH INTO SAID ZONE A SOUND OF HIGH INTENSITY ISTHERE CREATED.